1. Field of the Invention
The present invention relates to a glass workpiece locating system and method for locating a rectangular glass workpiece on a cutting table. The present invention further relates to a method of retrofitting existing cutting tables with the positioning system of the present invention.
2. Prior Art
FIG. 1 illustrates a conventional cutting table 10 which is utilized for locating, squaring and cutting a rectangular glass workpiece having known dimensions. The conventional method of locating and squaring a rectangular workpiece on the cutting table 10 is to transport the workpiece in a transporting direction 12 by conveyors 14. The workpiece is conveyed in the transporting direction 12 until the workpiece abuts a first pair of stops 16. Upon contact between the workpiece and the first pair of stops 16, the conveyors 14 are stopped, and the workpiece is transported subsequently transversely to the transporting direction 12 against a second pair of stops or locators 18. The transportation transverse to the transporting direction 12 is carried out by a retractable conveyor 20 operating transverse to the conveyors 14. With the rectangular workpiece abutting against both the first pair of stops 16 and the second pair of stops 18, the workpiece has now been squared, and the cutting head assembly 22 can begin cutting the workpiece according to a predetermined pattern.
U.S. Pat. No. 3,424,357 to Curtze et al. discloses an automatic sizing and severing apparatus for rectangular glass workpieces similar to the prior art illustrated in FIG. 1. The Curtze et al. patent discloses an apparatus utilizing an air support table which is sloped from the horizontal. A glass workpiece is transported onto the table by conveyor rolls and then is subsequently allowed to float to a squared-up position by the air table. The work may also be driven into the squaring index by rolls positioned transverse to the conveying rolls. After the glass workpiece is appropriately squared, it can be severed by an automatic scoring mechanism which is controlled by a series of edge-sensing sensors. A photocell or sensor is mounted on the positioning bridge of the cutting head to sense the trailing edge of the glass workpiece while another sensing device is mounted within the air support table to detect the leading edge of the glass workpiece. The sensors cooperate to determine the relevant position of the glass workpiece to control the severing apparatus.
The prior art cutting tables disclosed in FIG. 1 and in the Curtze et al. patent require a complicated set of conveyors operating transverse to each other, at least one of which being retractable. Additionally, the transverse movement of the glass workpiece in these prior art systems increases the likelihood of damage to the specific workpiece.
Another known glass workpiece positioning system for a cutting table utilizes an edge sensor for determining the precise location of the workpiece. A conveyor will transport a workpiece onto the cutting table and stop, positioning the glass workpiece in an arbitrary location on the cutting table. An edge-detecting sensor will move across the cutting table until it has detected at least three edges of the workpiece sufficient so that the precise orientation of the glass workpiece can be determined. The movement of the cutting head assembly is adjusted according to the specific positioning of the glass workpiece. In this prior art system, the adjustment generally requires a rotation of the coordinate system to correspond to the orientation of the glass workpiece. This system represents a time-consuming and complex positioning system.